J. Ignjatovic, J.
University of Melbourne

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The reliability of DIVA test based on M2e peptide exceed those based on HA2 or NS1 peptides Tarigan, Simson; Sumarningsih, . .; Ignjatovic, J.
Indonesian Journal of Animal and Veterinary Sciences Vol 20, No 2 (2015): JUNE 2015
Publisher : Indonesian Animal Sciences Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (524.763 KB) | DOI: 10.14334/jitv.v20i2.1167

Abstract

One of the most important disadvantage of vaccination against avian influenza is that it cannot protect vaccinated birds against infection. When vaccinated poultry are heavily exposed to the virus, prolonged, unrecognised, subclinical infection may persist on the farm. The condition can only be serologically monitored by a DIVA (differentiation of infected from vaccinated animals) test, whereas conventional diagnostic tests cannot be used. The DIVA tests based on an antibody response following virus replication is the most appropriate approach. For H5N1 influenza such antibodies includes those to the M2e and NS1 proteins and an epitope on the HA2 subunit (HA_488-516). The purpose of this study was to compare the magnitude of the antibody  response in chickens vaccinated and infected with an H5N1 virus strain. For that purpose, sera collected from naïve, vaccinated and infected  birds, at 1, 2-3, ≥4 weeks post challenge were used. Antibodies were measured by ELISA using biotinylated synthetic peptides as coating antigens. The peptides used include four NS1 peptides corresponding to different regions of the NS1 protein and HA_488-516and M2e peptides. Peptides were coated onto microtitre plates either directly or via a streptavidin bridge. The results showed that vaccination did not cause antibody conversion to any of the peptides, where as challenged birds developed a high antibody response to M2e but, low response to the NS1 and HA2 peptides. Antibodies to the later peptides were detected only by the streptavidin-peptide ELISA. The ELISA based on NS1 or HA_488-516 peptides, therefore, are not reliable for use as DIVA test in H5N1 avian influenza virus infection. Key Words: M2e, NS1 Protein, HA2 Peptide, DIVA Test, H5N1
Circulating H5N1 virus among native chicken living around commercial layer farms Tarigan, Simson; Indriani, Risa; Ignjatovic, J.
Indonesian Journal of Animal and Veterinary Sciences Vol 20, No 3 (2015): SEPTEMBER 2015
Publisher : Indonesian Animal Sciences Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (510.948 KB) | DOI: 10.14334/jitv.v20i3.1190

Abstract

Soon after the application of vaccination programme against high pathogenic avian influenza H5N1 outbreak of the disease in breeder and commercial layer farms has diminished remarkably in West Java. This study aimed to investigate whether the H5N1 decline is related to the disappearance of source of infection around the farms. Serum samples were collected from 421 native chicken living around commercial layer farms in the Districs of Cianajur and Sukabumi, West Java in March-April 2014.  Antibodies to avian influenza virus (AIV) H5N1 were measured using haemaglutination inhibition (HI), ELISAs and immunoblotting that measured presence of antibodies to the haemagglutin of H5N1 strain, as well as the M2e and nucleoprotein (NP) of all avian influenza viruses. Based on the combined results, 8.6% of the native chickens were seropositive to AI virus based on one or more of serological tests. This study provided serological evidence that H5N1 virus was still circulating among native chicken living around commercial layer farms. Many positive sera were however positive for antibodies in one test only: 2.4%, 3.3% and 3.8% by HI test, M2e and NP ELISA, respectively. It could be speculated that the incongruity of the results is due to the fact that HI, MM2e ELISA and NP ELISA all measure different type of antibodies and the duration of these antibodies in serum following infection with H5N1 differ. The fact that H5N1 virus is still circulating around commercial layer farms infers that the commercial farms are still under threat and therefore vaccination and strict biosecurity are still needed. Key Words: H5N1, Native Chicken, Commercial Layer, Nucleoprotein, M2e, HI Test